Propeller blade



July 26, 1938.

T. A. DlcKs 2,124,549

PROPELLER BLADE Filed Jan. 17, 1958 2 Sheets-Sheet 1 Qwucnboz UNO/mm1 Patented July 26, 1938 UNITED sTATEs PATENT OFFICE raoPELLEa BLADE Thomas A. Dicks, Pittsburgh, Pa. Application January 17, 193s, serial No. 185,415

26 Claims.

The present invention relates to aircraft propellers and particularly to reinforced hollow metal blades for such propellers.

Increased speeds and enlarged power plants in airplane designs practiced at present and in those planned for the future are imposing heretofore unknown demands upon the physical characteristics of all of the parts of such ships and especially is this true of propeller constructions. Until fairly recently, solid propeller blades have been utilized to a Ylarge extent, requiring frcquent modiflcation in size and number in an effort to cope with the rapid developments in airplanes and their engines. Such solid blades of adequate strength are inherently heavy, and already the efficient limits of size and number thereof have been exceeded in current manufacture.

Hollow metal blades have also been proposed and manufactured to some extent, but their general adoption has been retarded by certain deficiencies accompanying various modes of construction. Without regard to the excessive strains and fractures to which they subjected the metalsl used, a number of prior inventors have employed folded or lapped edges in their constructions, resulting in invariable failure under the tests to which they are subjected in accordance with requirements of tests now accepted as standard. Moreover, the higher speeds and greater vibrational effects set up a so-called bellows action in hollow blade constructions eventually causing them to become shattered under load.

Marked improvements in hollow blades have resulted from the use of internal reinforcing ribs extending between the pressure and camber faces, 'although many such constructions have still retained the objectionable sharp bending at the blade edges.

Another trend in the production of reinforced blades utilizes an internal rib which is secured to one or both, faces of the blade by spaced rivets, in some cases formed by welding. Such constructions are inadequate however to stand up under the bellows effects produced at the higher speeds, since there is a marked tendency for the rivets to fracture and the blade walls to become loosened and ultimately pull away from the edges of the reinforcing ribs even though the rivets have been relatively closely spaced.

Applicant has already made substantial advances over the prior art in his copending application Serial No. 155,770 nled July 26, 1937, and in the present application sets forth certain additional improvements in the production of reinforced hollow metal propeller blades characterized by their increased strength, simplicity of construction and accordingly, low cost.

By the present construction, a reinforced sheet metal propeller blade is formed from a plurality of sheets or plates of metal which are first shaped into blanks of suitable contour and taper, then pressed or otherwise bent to desired shapes and suitably joined together to constitute the complete blade, including the reinforcing rib, the root end, the pressure face, the camber face, the leading edge, the trailing edge and the tip. As in applicants prior Patent 1,713,500, granted May 14, 1929, the joints of the present construction are formed by welding the plates together in such a way that the joints will not interfere with the necessary aerodynamic design nor impart weakness where strength is desired. Moreover, at no point in the construction is it necessary to bend the metal elements of the present construction upon such a small radius that there is any danger of fracture or fatigue.

One face of the blade proposed in accordance with the present construction is made up of a plurality of longitudinally extending sheets or plates welded at their meeting edges to form a joint or joints intermediate of the face. The outermost edges of these plates extend substantially to the leading and trailing edges of the blade 3o where they are welded to the sheet metal materia! constituting the opposite face. It is contemplated that the opposite falce be formed from a unitary sheet of metal, but in some cases a plurality of sheets may be welded together. A reinforcing rib is rigidly secured to both faces of the blade and extends from the welded joint intermediate one of the faces to the opposed face and is welded to the latter as well. This reinforcing rib may be integral with one of the plates aforesaid, or may in some cases be entirely sep arate and attached solely by welding.

In accordance with the preferred construction .of the present invention, one of the faces of the blade is defined by a unitary sheet or blank of metal which is also shaped to define the root end of the blade. The opposite face in this preferred form is constituted by two separate metal sheets or blanks which are joined together and to the unitary sheet by welding. One of the two sheetsl constituting the second face is 'suitably folded or pressed to dene the rib forming element extending substantially perpendicular thereto. During assembly this rib is welded to the internal wall of the unitary blank constituting the first face. -In accordance with this same preferred construction, one of the faces of the blade will contain no welded joints externally thereof and the opposite face will contain three welded joints. two of which are near the edges and the third intermediate of the face.

The blanks from which the ribs and faces are formed are preferably tapered from the root end of the blade towards the tip in accordance with applicants prior disclosures herein referred to.

A more detailed understanding of the present invention and its objects will be possible by referring to the accompanying drawings.

Fig. l is a plan view of the propeller blade wherein the camber face is formed from a single blank and the welded joints are formed in the pressure face;

Figs. 2 to 12 are sections taken along lines 2-2 to I2-I2 respectively of Fig. 1;

Figs. 13, 14 and 15 are sections corresponding respectively to Figs. 4, and 6 of a modification;

Figs. 16, 17 and 18 are sections also corresponding generally to Figs. 4, 5 and 6 of a further modification;

Fig. 19 is a plan view of a propeller blade wherein the pressure face is formed from a unitary blank and the welded joints are formed in the camber face;

Figs. 20 to 30 are sections taken along lines 20--20 to Sli-3B respectively of Fig. 19;

Figs. 31, 32 and 33 are sections corresponding generally to Figs. 22, 23- and 24 of a modification; and

Figs. 34, 35 and 36 are sections likewise corresponding generally to Figs. 22, 23 and 24 of a modification.

The hollow sheet metal propeller blade depicted by Fig. l of the drawings comprises a root end 40, a leading edge 42, a trailing edge M, a tip 46, a camber or suction face 48 as shown in the sectional views, and a pressure or working face 50.

As will appear from the sectional views shown in Figs. 2 to 12, the blade is provided with an internal reinforcing rib il which extends the full length of the working portion of the blade, namely from the rounded or otherwise conformed portion of the root end of the bladeto the tip thereof. In these sections the reinforcing rib is integral with one of the blanks utilized in forming a face of the blade and has its edge welded to the internal wall of the other of the 'blade faces.

The blade conforming to the modification of Figs. 1 to 12 is constructed from three blanks or sheets. .A blank 54 is suitably pressed or otherwise formed to define the camber face of the blade, the root end thereof, and essentially, the leading and trailing edges. Where the radii of the leading and trailing edges of the blade are relatively large as shown in Figs. 4 and 5, the blank 54 is bent sufficiently to define these edges entirely. As the radii or angularity of the edges decrease however, the edges of the blank 5l undergo progressively. reduced bending as will appear from the sectional views of' Figs. 6 to 12. The pressure face 50 of the blade in this embodiment is made up of a pair of blanks or plates 5B and 58 whose outer edges extend to points adjacent the trailing and leading edges of the blade respectively and contiguous to the edges of the unitary blank of the camber face. At these outer edge portions, the plates are uhited by means of welded joints 60 and 62 respectively to the contiguous edges of the unitary blank 5l defining the camber face.

The rib 52 in this form of the invention is integral with the blank 58 which may be termed the leading edge blank of the pressure face. The rib is formed by suitably pressing or folding on a reasonably large radius to avoid fractures and extends at substantially right angles from the face forming portion of the blank. The rib is secured to the internal wall of the camber face by means of a welded joint 64 extending continuously from the root end of the blade to the tip thereof as clearly depicted by broken lines in Fig. 1. The two plates 56 and 58 constituting the pressure face are connected intermediate of this face by a welded joint 66, which merges into the welds 60 and 62 near the root end of the blade and again near the tip thereofA The free edges of the blank 54 forming the root of the blade are also united by a welded joint 61.

The modification of this construction shown in Figs. 13, 14 and 15 contemplates the rib 52 as integral with the trailing edge plate 5B of the pressure face instead of the leading edge plate 52. This modification is otherwise similar to.

the construction already described.

The modification appearing in Figs. 16, 17 and 18 employs an entirely separate element to serve as the rib 52 which is joined to not only the camber face by its welded joint S4 but likewise to the pressure face plates 56 and 58 by the welded joint B6 whichunites these two plates as well, as in the previously described construction.

As will be noted by observation of Figs. 2 to 12 inclusive, the metal constituting the blanks is tapered from the root end of the blade towards the tip thereof in order to obtain a balanced construction of adequate strength. If desired, the root end itself may be of uniform thickness in order to possess suilcient strength for attach,- ment to the hub of the propeller. 'Ihe elements of this construction are first produced in sheet form of desired thickness and taper. whereupon they are bent or folded to substantially their final shape. to the unitary blank at 64 while holding the respective parts in position by suitable collapsible mandrels. After this operation has been com pleted the blanks defining the faces of the blade are mutually welded together to form the joints 6l), 62 and 66 while still supporting the parts by collapsible mandrels. After removal of the mandrels, the welding may be completed at the tip and at the root end of the blade whereupon the assembly is ready for its finishing operations.

The modification of the invention shown in Figs. 19 to 30 inclusive contemplates a unitary plate 68 for the pressure face 50 of the" blade and a plurality of plates defining the camber face 48 thereof. In this instance the reinforcing rib 52 is integral with one of the plates defining the camber face 4B. Specifically, the rib is integral wlth and substantially perpendicular to the leading edge plate 1I) of the camber face which is united by the weld 6B to the trailing edge plate 1 2 of the camber face. In view of the Vfact that all of thewelds in this modification occur in the camber face. they have been indicated by dotted lines in Fig. 19.

The modification in Figs. 31, 32 and 33 varies from the form in Figs. 19 to 30 inclusive only in the provision of the reinforcing rib 52 as integral with the trailing edge plate 12 of the camber face as distinguished from its integral relationship with respect to the leading edge plate of the preceding figures.

In Figs. 34, 35 and 36, the reinforcing rib 52 has been depicted as a separate element joined The rib 52 is preferably iirst welded extending from said intermediate to the camber face plates lil and 'if by a common welded joint 66 and to the internal wall of the pressure face by the welded joint 6I.

The manner of assembly of the elements constituting the blade shown in the modicatlon of Figs. 19 to 36 is analogous to the method described with reference to Figs. i to i8 inclusive.

The modifications of the invention which have been described are by no means exhaustive of the constructions possible in accordance with the present invention and are therefore intended to serve by way of illustration and not by way of limitation. Accordingly, this invention should not be restricted beyond the scope of the appended claims.

I claim:

i. A propeller blade comprising one face substantially defined by a unitary blank, an opposed face substantially defined by a plurality of blanks, welded joints connecting said blanks and a reinforcing rib extending from said opposed face to said unitary blank.

2. A propeller blade comprising one face sub stantially defined by a unitary blank, an opposed face substantially defined by a plurality of blanks, welded joints connecting said blanks and a reinforcing rib integral with a blank of said plurality of blanks extending from said opposed face to said unitary blank.

3. A propeller blade comprising one face substantially defined by a unitary blank, an opposed face substantially defined by a plurality of blanks, welded joints connecting said blanks and a reinforcing rib extending from said opposed face to said unitary blank, said rib being welded to blanks of both of said faces.

4. A propeller blade having a pressure face, a camber face, a leading edge and a trailing edge, a unitary blank defining one of said faces, the other of said faces being dened by a pair of blanks extending from a portion intermediate thereof substantially to said edges and a rein forcing rib extending from said intermediate portion to the opposite face.

5. A propeller blade having a pressure face, a camber face, a leading edge and a trailing edge, a unitary blank defining one of said faces, the

other of said faces being defined by a pair of blanks extending from a portion intermediate thereof substantially to said edges and a reinforcing rib integral with one blank of said pair opposite face.

6. A propeller blade having a pressure face, a camber face, a leading edge and a trailing edge, a unitary blank defining'A one of said faces. the other of said faces being deiinedby a pair of blanks extending from a portion intermediate thereof substantially to said edges and a reinforcing rib integral with the blank of said pair which extends towards the leading edge, extending from said intermediate portion to the opposite face.

"I. A propeller blade having a pressure face, a

' camber face, a leading edge and a trailing edge,

a unitary blank defining one of said faces, the other of said faces being dened by a pair of blanks extending from a portion intermediate thereof substantially to said edges anda reinforcing rib integral with the blank of said pair which extends towards the trailingedge, extending fromv said intermediate portion to the opposite face.

8. A propeller blade comprising a camber face defined by a unitary blank, a pressure face deportion to the fined by a pair of blanks joined intermediate the face and a reinforcing rib extending from the intermediate portion of said pressure face to said camber face.

9. A propeller blade comprising a camber face defined by a unitary blank, a pressure face defined by a pair of blanks joined intermediate the face and a reinforcing rib integral with one blank of said pair extending from the intermediate portion of said pressure face to said camber face.

i0. A propeller blade comprising a pressure face defined by a unitary blank, a camber face defined by a pair of blanks joined intermediate the face and a reinforcing rib extending from the intermediate portion of said camber face to said pressure face.

1 1. A propeller blade comprising a camber face, a pressure face, a leading edge and a trailing edge, a unitary blank substantially defining said camber face, a blank extending from said leading edge partially defining said pressure face, a blank extending from said trailing edge completing said pressure face and a reinforcing rib extending between said faces. v

12. A propeller blade comprising a camber face, a. pressure face, a leading edge and a trailing edge, a unitary blank substantially defining said camber face, a blank extending from said leading edge partially defining said pressure face, a blank extending from said trailing edge completing said pressure face and a reinforcing rib integral with one of the pressure face blanks extending between said faces.

13. A propeller blade comprising a camber face, a pressure face, a leading edge and a trailing edge, a unitary blank substantially defining said camber face, a blank extending from said leading edge partially defining said pressure face, a blank extending from said trailing edge completing said pressure face and a reinforcing rib integral with the first of said pressure face blanks extending between said faces.

i4. A propeller blade comprising a. camberl face, a pressure face, a leading edge and a trailing edge, a unitary blank substantially defining said camber face, a blank extending from said leading edge partially defining said pressure face, a blank extending from said trailing edge completing said pressure face and a reinforcing rib integral with the second of said pressure face blanks extending between said faces.

15. A propeller blade comprising one face substantially defined bya unitary blank, an opposed face substantially defined by a plurality of blanks, welded joints connecting said blanks and a reinforcing rib extending from said opposed face to said unitary blank, one of said blanks also de'- iining the root end of the blade.

16. A propeller blade comprising a camber face defined by a unitary blank, a pressure face defined by a pair of blanks joined intermediate the face and a reinforcing rib extending from the intermediate portion of said pressure face to said camber facegand from the root end to the tip of the blade.

17. A propeller blade comprising a pressure camber faces denned by s plurality er blanks, 'rs

welded joints adjacent the leading and trailing edges of the blade, an internal reinforcing rib extending between said faces and secured in position by welding, and a welded Joint extending continuously along an intermediate portion ot one of said faces.

19. A propeller blade comprising a camber face substantially defined by a single sheet of metal, a pressure face partially dened by a. second sheet of metal and completed by a third sheet of metal, welded joints between said sheets along the leading and trailing edges and intermediate said pressure face, and a reinforcing rib extending from the weld intermediate said pres- 10 sure face and welded to said camber tace.

THOMAS A. DICKS.

DISCLAIMER 2,124,549.-Thomas A. Dicks,

July 26, 1938.

Pittsburgh, Pa. Disclaimer filed January 17, 1940, by

Pat-ent dated the inventor; the

PROPELLER BLADE.

Hereby enters this disclaimer to 18, 19, and 20.

[Oficial Gazette February 13, 1.940.]

Claims 1, 2, 3, 4,5, 6, s, 9,11, 12, 13, 15, 16,

welded joints adjacent the leading and trailing edges of the blade, an internal reinforcing rib extending between said faces and secured in position by welding, and a welded Joint extending continuously along an intermediate portion ot one of said faces.

19. A propeller blade comprising a camber face substantially defined by a single sheet of metal, a pressure face partially dened by a. second sheet of metal and completed by a third sheet of metal, welded joints between said sheets along the leading and trailing edges and intermediate said pressure face, and a reinforcing rib extending from the weld intermediate said pres- 10 sure face and welded to said camber tace.

THOMAS A. DICKS.

DISCLAIMER 2,124,549.-Thomas A. Dicks,

July 26, 1938.

Pittsburgh, Pa. Disclaimer filed January 17, 1940, by

Pat-ent dated the inventor; the

PROPELLER BLADE.

Hereby enters this disclaimer to 18, 19, and 20.

[Oficial Gazette February 13, 1.940.]

Claims 1, 2, 3, 4,5, 6, s, 9,11, 12, 13, 15, 16, 

